Patent GB-1112704-A (GB)
Title: Process for the manufacture of multi-ply constructions
IPC: C08J5/12
Filed: 1966-01-31
Abstract: 1,112,704. Laminates and laminating. CHEMISCHE WERKE ALBERT. 31 Jan., 1966 [29 Jan., 1965], No. 4187/66. Heading B5N. A process for the manufacture of a laminate comprising a substantially rigid foam bonded to a lamina, or interposed between two laminµ, comprises the steps of coating at least one surface of the lamina or each of the laminµ with an adhesive comprising an acid-hardenable and/or heat-hardenable synthetic resin; evaporating any volatile component of the adhesive without substantial hardening of the resin; contacting with said coated surface, or surfaces a foamable mixture comprising a hardenable phenol-formaldehyde resin, a propellant, and an acidic hardening catalyst; foaming and hardening said foamable mixture and also hardening said adhesive, whereby a laminate is obtained having a substantially rigid foam of phenol-formaldehyde resin bonded to said lamina or laminµ. As described, the lamina or laminµ may be plates or tubes of a metal, e.g. aluminium or degreased steel, or of paper, cardboard, asbestos cement, wood, glass, or synthetic material. The adhesive, which may be painted or sprayed on to the lamina(e) preferably becomes tacky on heating, is heat-hardenable between room temperature and 100‹ C. and is hardenable in the presence of acids. The hardenable synthetic resin present in the adhesive may be urea- or melamine-formaldehyde resin but phenol-formaldehyde resin is preferred. The adhesive resin is preferably plasticized with a drying or non-drying alkyd resin, and may be unetherified or its methyl groups may be etherified with monohydric alcohols containing 1 to 4 carbon atoms (examples given). The adhesive may include additives to improve its adhesion, e.g. thermoplastic synthetic resins or organic silicon compounds, preferred additives being polyvinyl acetals, e.g. polyvinyl butyral, or other polyvinyl compounds, e.g. polyvinyl acetate. The phenol-formaldehyde resin included in the foamable mixture may be those derived from mono- or polyhydric phenols, e.g. phenol, o-, m- or p-cresol, resorcinol, pyrocatechol, hydroquinone, and diphenylol propane. The acidic catalyst used in the foamable mixture may be a strong mineral or organic acid, e.g. sulphuric acid, phosphoric acid, or p-toluene sulphonic acid, and is preferably a volatile acid, e.g. hydrochloric and/or hydrobromic acid. The preferred propellants are petroleum fractions boiling in the range 25- 80‹ C., but ethers, fluorinated and/or chlorinated hydrocarbons, or compounds evolving gases under the action of acids and/or heat, e.g. calcium carbonate or certain azo compounds, may be used. In the process described, the phenol-formaldehyde resin, propellant, and catalyst are mixed just before the foam is required. Foaming usually commences at room temperature, but heat may be applied to accelerate foaming and hardening. In the process in which two rectangular laminµ are used, these are supported in a frame closed on three sides foaming taking place between the laminµ and excess foam being expelled from the fourth, open, side of the frame. The laminates produced by the process may be used as building materials for heat and sound insulation, or as packing material.